On Mon, Sep 03, 2018 at 07:37:56PM -0700, Stephane Eranian wrote:
SNIP
>
> I think the code is correct now for the issue related to uninitialized
> pointer.
> But there is still one problem I found stressing the code with max_alloc_size.
> The way the following is written:
>
> if (!list_empty(cache)) {
> new = list_entry(cache->next, struct ordered_event, list);
> list_del(&new->list);
> } else if (oe->buffer) {
> new = oe->buffer + oe->buffer_idx;
> if (++oe->buffer_idx == MAX_SAMPLE_BUFFER)
> oe->buffer = NULL;
> } else if (oe->cur_alloc_size < oe->max_alloc_size) {
> size_t size = sizeof(*oe->buffer) MAX_SAMPLE_BUFFER *
> sizeof(*new);
>
> oe->buffer = malloc(size);
> if (!oe->buffer) {
> free_dup_event(oe, new_event);
> return NULL;
> }
>
> pr("alloc size %" PRIu64 "B (+%zu), max %" PRIu64 "B\n",
> oe->cur_alloc_size, size, oe->max_alloc_size);
>
> oe->cur_alloc_size += size;
>
> You can end up with oe->cur_alloc_size > oe->max_alloc_size in case
> the max limit is
> really low (< size_t size = sizeof (*oe->buffer) + MAX_SAMPLE_BUFFER *
> sizeof(*new);
> So I think to make sure you can never allocate more than the max, you
> have to do:
>
> size_t size = sizeof(*oe->buffer) MAX_SAMPLE_BUFFER * sizeof(*new);
> if (!list_empty(cache)) {
> new = list_entry(cache->next, struct ordered_event, list);
> list_del(&new->list);
> } else if (oe->buffer) {
> new = oe->buffer + oe->buffer_idx;
> if (++oe->buffer_idx == MAX_SAMPLE_BUFFER)
> oe->buffer = NULL;
> } else if ((oe->cur_alloc_size + size) < oe->max_alloc_size) {
>
> Then you will never allocate more than the max.
> I think with this change, we are okay.
> Tested-by: Stephane Eranian <eran...@google.com>
yep, makes sense.. something like below then
I'll post it on top of the previous patch
thanks,
jirka
---
diff --git a/tools/perf/util/ordered-events.c b/tools/perf/util/ordered-events.c
index 87171e8fd70d..2d1d0f3c8f77 100644
--- a/tools/perf/util/ordered-events.c
+++ b/tools/perf/util/ordered-events.c
@@ -101,6 +101,7 @@ static struct ordered_event *alloc_event(struct
ordered_events *oe,
struct list_head *cache = &oe->cache;
struct ordered_event *new = NULL;
union perf_event *new_event;
+ size_t size;
new_event = dup_event(oe, event);
if (!new_event)
@@ -133,6 +134,8 @@ static struct ordered_event *alloc_event(struct
ordered_events *oe,
* Removal of ordered event object moves it from events to
* the cache list.
*/
+ size = sizeof(*oe->buffer) + MAX_SAMPLE_BUFFER * sizeof(*new);
+
if (!list_empty(cache)) {
new = list_entry(cache->next, struct ordered_event, list);
list_del(&new->list);
@@ -140,10 +143,7 @@ static struct ordered_event *alloc_event(struct
ordered_events *oe,
new = &oe->buffer->event[oe->buffer_idx];
if (++oe->buffer_idx == MAX_SAMPLE_BUFFER)
oe->buffer = NULL;
- } else if (oe->cur_alloc_size < oe->max_alloc_size) {
- size_t size = sizeof(*oe->buffer) +
- MAX_SAMPLE_BUFFER * sizeof(*new);
-
+ } else if ((oe->cur_alloc_size + size) < oe->max_alloc_size) {
oe->buffer = malloc(size);
if (!oe->buffer) {
free_dup_event(oe, new_event);
